A corpectomy is the excision of one or more vertebral bodies, usually combined with replacement of the removed body or bodies with a prosthesis or bone graft. A corpectomy may be necessary to correct a degenerative condition, to treat a traumatic injury, to replace vertebral bodies damaged by tumors or other diseases, or in other situations as deemed appropriate by a physician.
Implants and methods useful in performing corpectomy procedures have been known in the art for a number of years. Many of the previous implants and methods sought to create fixed constructs designed to eliminate relative movement between the vertebrae to which the implants were attached. Fixed constructs have been used with some success. However, it is difficult to achieve a securely fixed construct with a corpectomy device because the distance between the fixed vertebrae is relatively large. Consequently, in practice, some amount of motion typically occurs at the interface of the corpectomy device and the vertebrae. The motion may be very small—sometimes called “micro-motion.” Nonetheless, even micro-motion applied through a large number of cycles can cause loosening of an implant. Loosening may necessitate corrective surgery with its associated cost, pain, and inconvenience.
Fixed constructs may also be limited because they fail to provide interfaces with the vertebrae that easily adapt to physiologically unusual, deformed, diseased, or damaged vertebral body surfaces. It is common practice to chisel or machine away portions of a vertebra to make the vertebra conform to an implant. This may cause additional surgical time and expense, and trauma to a patient.
Some of the prior implants and methods provided ball-in-socket or hinged connections rather than fixed constructs. Such flexible joints can be problematic because they may not provide an adequately stable construct to support a patient's weight and activities, especially where the patient has experienced soft tissue damage or degeneration at or near the corpectomy site.
The description herein of certain disadvantages and problems associated with known devices, apparatus, and methods is not intended to limit the scope of the invention to the exclusion of those known devices, apparatus, and methods. Indeed, embodiments of the invention may include some or all of the known devices, apparatus, and methods without suffering from the disadvantages and problems described herein.